BERLIN (Reuters) - Germany's auction of frequencies for next-generation 5G networks will begin as planned on March 19, the Federal Network Agency (BNetzA) said on Friday, after a court threw out challenges brought by the country's three operators.

Deutsche Telekom, Vodafone and Telefonica Deutschland had filed motions seeking to put the auction on hold, complaining that the terms under which spectrum was being sold off were onerous.

"The date stands," a BNetzA spokeswoman said, confirming the auction would start at 10 am (0900 GMT) next Tuesday in Mainz.

The Cologne Administrative Court, ruling on the matter, found the BNetzA had acted within its powers to require network operators to commit to providing fast network coverage covering 98 percent of households by 2022 to qualify for the auction.

The court's decision is final.

It averts a possible delay to Germany's rollout of 5G networks that can support ultra-fast home internet or run high-tech 'connected' factories.

German industry and mobile consumers already have to contend with network coverage that ranks poorly among peers, and any delay risked leaving Europe's largest economy lagging further behind early 5G adopters like the United States, Japan or Korea.

Telefonica Deutschland said it would review the decision. It added, however, that should a separate legal challenge filed late last year succeed, there was a risk that the results of the auction could be retroactively cancelled.

Vodafone declined to comment, while Deutsche Telekom was not immediately available for comment.

The trio has been admitted by the BNetzA to take part in the auction, along with potential new entrant 1&1 Drillisch, the mobile virtual network operator controlled by United Internet.